Motion conversion mechanism



March z, 1943. w. J. ULBm-SON 24,312,318

' MOTION. CONVERSION MECHANISM Filed oct. 17, 1941 s sheets-sheet 1 March 2, 1943. w. J. QULBERTSON 2,312,318

' MOTION CONVERSION MEQHANISM Filed oct. 17, 1941 s sheets-sheet 2 lil 25 2f MalCh 2, 1943' w. J. cuLBl-:RTsoN v MOTION CONVERSION MECHANISM File-d Oct. 17, 1941. 3 Sheets-Sheet 3 {NVNTOR Will/'am J. Cu/berfson Patented Mar. 2,1 943 y Morton ooNvEnsIoNMEoHANIsM William 1. Culbertson1 Brocton, Ill. A Applicata october 11, 1941,'ser1a1 No. 415,384, p (cl. rfa-52) comms.

This invention relates to mechanisms for lthe conversion of the reciprocating` motion of a piston in a cylinder or other type of back-and-forth, straight-line motion into rotary motion `or the 'conversel and is intended to ksupplantthe time honored, orthodox system' of connecting-rods and-crank drive, now in common use Iin engines,

pumps, compressors and other machines.

vA general object of this -invention is the provisions of simplified, improved means of connecting the pistons of a radial cylinder type, oro'f an opposed cylinder type, or of an `opposed-piston, single or double-acting, opposed'or tandem cylinder type engine, pump, "compressor, etc., to the crankshaft. f' Y f V A further object'of this invention is the prof vision of a kind of driving gear mechanism, which makes possible the attainment of perfect balance and smooth running. of all reciprocating `lland rotating parts of the completej'engine f vthroughout its entire speed r'ange. Inasmuch as there are no parts of the drive mechanisms, having an oscillating, angular or irregular motion,

' the error in the` pistons position, due to'jthe Obliquity of the connecting rod of the usual orthodox type of engine'drive, is eliminated. All plstonrods and other reciprocating members of this 4driving gear move withtrue harmonic motion.

The provision of thoroughly practical simplifled driving gear mechanisms, such as those described herein, make possible the following improvements in an `enginez-,Permits the installation of stuffing boxes `on the piston rods, between the crankcase and the cylinders, thereby completely isolating the one from the other, thus insuring controlled cylinder wall lubrication; prevents pollution of the crankcase by leakage from piston liquid cooling equipment; makes possible the complete isolation of the cylinder wall heat from the crankcase; all made possible without requiring the use of a cross-head, which adds materially to thelength or height of the engine. Permits elimination of all oscillating, hard to lubricate, wrist-pin bearing surfaces in the heated area directly `under the piston head; simplifies the design of suitable apparatus for the liquid cooling of the 'piston head surfacesr of large bore engines; permitsreduction of the length of fo'r the piston to function as a ring carrieror interrupter, thus permitting the exposure of .a large percentage of the `heated cylinderwall surface,

ito the cooling effect of the scavenging air, etc.

Completely eliminates that part'of the power lost through friction, betweenthe piston and cylinder wall surfaces, caused by the side thrust exerted on `the ordinary trunk type piston,` which is in common use. Obviates the-necessity of employing widely separated crankshaftsxconnected by an idler gear train, or by a lay shaft and bevel gears, or by a silent chain,for by othermeans,

now in common use in4 engines* of the opposedpistcntype;y provides the first really simplified,

practicalxdriving gear for a `double-acting, op-v posed-pistomco-axial cylinder type engine. Further-objects and advantages will appear from the detailed descriptions of the driving gear mechanisms, yembodying the invention in 'the present preferred forms, hereinafter submitted, the description being considered-in connection with the accompanying drawings. v

These mechanisms are of the type inA which one or more eccentric sheaves are fixed toa sleeve and rotatably mounted upon the crank pin of a crankshaft, straps on the eccentric sheaves being connected, through piston rods or otherwise, to the reciprocating members, the throws of the crank and eccentric vsheaves all. being made equal and the movementfof the eccentric sheaves with respect i to the crankshaft so constrained that the center points of all of the eccentric sheaves move in straight-line paths, which pass vvthrough the axis 'of crank rotation. n

Ithas been known for many yearsvthat, if the eccentric sheaves, including the sleeve upon which theyare eccentrically mounted, are constrained in some positive manner, such as Awill force or require them to rotate aroundthe ycrank pin, in the opposite direction of rotation from, but with the same absolute angular velocity as, the crank pin rotatesabout the crankshaftaxis, then the centerv points of the eccentric sheaves and of the eccentric straps operatively mounted thereo n will move with a reciprocatory, harmonic motion in rectilinear` paths, which pass through the axis of crank rotation, the extent of this straightline travel, back-arid-forth across the crank axis,

being equal to four times the throw of the crank. 1

Geometrically, this action or method of transformation of motion is explained bythe fact that any point on the circumference of a smaller circle rolling on the inside of and tangent internally to a fixed circle of twice the diameter, describes a straight-line path, whichl passes through the center point of and is actually the diameter of the-larger fixed circle; the extent, in any one direction, of this straight-line path, which, if the motion is continued, is of a reciprocating back-and-forth type,'is` equal to twice the diameter of the smaller circle; the movement of this point on the circumference of the smaller circle aroundthe center of the smaller circle being in thel opposite direction of rotation from, but at the same absolute angular velocity as, the

circular motion of the` center of the smaller circle around the lcenter-of the larger circle.V These geometric relations constitut'ea theorem,` long established in mathematics,v butnevgr before 1 successfully applied in a commercial, practical way, to the conversion of reciprocating motion` to; :Y rotary' motion as in steam engines, internal com,- bustion engines, etc., or the coi'iverse as in plunger pumps, compressors, etc. n

The following parts Vand conditionsv regarding same are embraced in each andl every motion conversion mechanism herein described.l A sleeve is rotatably mounted on a crank pinofthe crank of a crankshaft whiclgis supported on bearings. One or more eccentric sheaves and a pinion are rigidly fixed to the sleeve and an eccentric strap is operatively mounted on each eccentric sheave. The eccentricity or throw of all eccentric sheaves fixed tothe sleeve is made equal to the throw of the crank. The pinion on the sleeve meshes direct with an internal gear, which is mounted in a fixed position on ayoke, the pitch diameter of the internal-gear being made twice the pitch diameter of the pinion. The center. point of the internal gear must always be maintained at some point on the pitch circle of the pinion. The yoke, including the internal gear fixed thereon, is maintained in a circular motion of such a nature that any straight line selected on'the yoke always remains parallel to the same straight line on the yoke in any "other position ofthe yoker movement` Inlother words; any diameter of the internal gear securedA to the yoke is maintained parallel to itself in' all positions of the crank movement. The angular velocity of the circular yoke motion and the direction of movement lare made the same as lthose of the crank. The axis around which the yoke and internal gear move I coincides with the axis of crank rotation. The

diameter of the circular ,path traversed by the yoke and the fixed angular position of the internal gear center point with lrespect to the crank pin, around their common axis of rotation, are made such that the pinion and internal gear are maintained in constant proper mesh in all positions ofthe crank movement. The pitch diameter of the pinion is made greater than twice the throw of the crank.

In the accompanying drawings, which illustrate several embodiments of the invention:

Fig. 1 is a vertical transversesection through a crankshaft taken on the lineI-I of Fig. 2, showing the associated mechanism;

Fig. 2 is a vertical longitudinal section taken on the line II-II of Fig. l, parts being shown in elevation;

Fig. 3 is a horizontal transverse section taken on the line III-III of Fig. 1;

Fig. 4 is a vertical transverse section through the crankshaft of a modified type of motion conversion mechanism, partially cut away and taken Fig.- 7 is a horizontal longitudinal section'takeny on the line VII-VII of Fig. 6.

Referring now more particularly to the drawings and for the present to the embodiment illustrated in Figs. l, 2 and 3, a built-up type IsinglenorHmulti-throw crankshaft I supported by main bear/ings 2 mounted in the crankcase/has a sleeve 3.,.rotatably mounted on each of its crank pins l. One onmore eccentric sheaves 5 and a .pini'onl-S are madev integral with or rigidly fasvtricityorthrows.of alleccentic sheaves 5 :are

. adjacent crank pins 4 but there could be only a single eccentric sheave, pinil'in vand sleeve mounted on only one crank pin, if desired. Each of the eccentric sheaves 5 is provided with any eccentric strap 1 to which a piston rod 8 is connected and which receives and transmits the thrust from pistons (not shown), power being taken from one or both ends of th crankshaft or at a point between the ends of the same.

Each of the pinions 6 meshes directly with an internal gear 9 which has a pitch diameter twice that of the pinion '6, the internal gears 9 and yoke I2, to which they are attached, all being operatively mounted on the periphery IIJ of the eccentrically located webA or v'cheek II of the crankshaft I between adjacent crank throws, said periphery I0 forming the bearing surface of the yoke orframe I2, to which the internal gears 9 yare rigidly fastened. The center point I3 of the web periphery III and likewise of the'internal 'under operating conditions but which will permit some adjustmentl of the position of said gears with respect to the yoke, in a tangential direction about their center point Il; for the purpose of correcting possible misalignment of the piston rod path resulting from gear tooth wear. In order to permit such adjustment, the gear plates 9 are fastened to the yoke members I 2a with cap screws I5, the screw holes I6 in the gear plate being slotted to permit such adjustment. Other methods of adjustment may be used, if desired.

The yoke I2 to which the internal gears 9 are rigidly fastened is operatively mounted on the crank pins I8 of two auxiliary cranks or eccentrics I9 supported in bearings ISa in the crankcase, the throw e of each of these auxiliary cranks being made equal to the eccentricity e of the cen-1 ter point I3 of the internal gears 9 with respect to the axis I4 of the main crankshaft I, the angular position of each of the auxiliary crank pins I8 around their axes 20 of rotation being made the same as the angular positions of the internal l -2a1aa1e. gear center point I3 around the axis I4 ofthe n ance between-theilxed guides'andshoes, arepro-'H main crankshaft I, the angular velocity of the auxiliary crank pins I8 and their direction o f rotation being made the Vsame as that of the main pins I8 about the axes 20 of the auxiliary crankshafts I9 and the circular movementv of the yoke I2 which is operatively mountedon the auxiliary 'crankpins I8 is caused bv th. movement of. the

main crankshaft I about its-axis I4 as a-'result of kthe mounting of the' yoke onfthe eccentrically located peripheral bearing surface I ofthe web II of the main crankshafti, the diameter of the 1 l;,.f"f"l'he-throws e of eachof theauxiliary cranks f or eccentrics VI9 are jmade equal and likewise j equal to the distancefbetween the axis I4 of the main, crankshaft `I.a n`d the center point I3.of the circular path of the movement of eachy auxiliary crank pin I8 and yoke I2 being 2e. .'lhis-moveg!I ment of thel yoke I2 is of such Aa nature that any line` taken on" the yoke valways remains paralleliv to itself in all positions of the main crankmdvement. Likewise, since. the internal gearl9-is-r1gidly fastened to .the yoke I2, any diameterof the Ainternal gear 9 always remains parallel to itself in all positions of the lmovementof the mainv crank 1 I. 'Ihe auxiliary crankshafts I9, 'act in theca-` y l l 5 trically located `bearing"surface I0 of 'afweb of pacity of idler cranksdriven by the main crankshaft I throughI the yoke I2 acting as aconnecting link or rod, the primary purpose of these aux'-v iliary cranks being that of maintaining the yoke in a circular motionsuchthat it always remains parallel to itself in all positions of the crank -fnovement andr likewise insures they continuous proper engagement of. the pinions @with the internal gears 9.

Because there is no tangential movement of thev internal gear 9 with respect to its centerfpoinu I3, any lineon said gear 9 being always maintained parallel to itself for all positions ofthe A.

crank movement and because of the two to one gear ratio relationship of the internal gear 9 to the'pinion 6', said gears being maintained in continuous proper engagement by the circular movement of said internal gear!! as a result ofthe eccentric mountingofthis gear 9 and yoke I2 with respect to the axis I4 offthe main crank I,

theeccentricty of said mounting beingequal to e, the pinion 6,' attached vtoi'sleeve 3 and eccentric sheaves 5 al1l rotate Vat the same absoluteA angular;vv velocity as, but in the opposite direction of rotas,v

tion from, that of the main crank I, thereby f ulfilling all requirements necessary `to insure themen straight-dine movementofthe center points 26 of through the axis I4 of the main crank I; the' extent of saidmovement in any one direction being equal to four times the' throw T of the-'main crank I.

The twisting action exerted on the 'yoke I2 results :from the transmission of the gear loads between the pinions 6 and the internal gears 9,

' the planes of application of -these gear tooth forces being. on both sides ofthe center line of the web II of themain crankshaft I. 'Ihis twist.- ing action on the maintained'througl'rthe provision of suitable adjustabiy mounted shoes.. z2 provided with tearingr surfaces which slideiin 'a'circular pathA over' the surfaces of 'fixed guide plates 23 located 1n a plane normal to the axis I4 of the main crankshaft I, the guide plates 23 being either integral said eccentric sheaves 5, in pathsfwhich pass yoke. I2 is-counteracted and .proper operating alignment of said yoke I2 is vided on both sides ofthe fixed guide mates za I8 of the auxiliary cranks 'I9, these two side menibersv I 2a, together with the internal gears 9 being rigidly` fastenedHto--the 'central collar shaped memberl 25, which has a bearing'surface'v riding ori-the? periphery iii'of the web Il ofthe main crankshaft` I,v as shown in Fig. 2.-v l

internal gears-95 f'Althoughit is' preferred to 20 have .ftwo. auxiliary "crankshafts` I9 .operatively connectedto the yoke I2, it Ais' possible, "in the i l mechanism illustarted in Fig. 1,A to dispense with i one 'of' the auxiliary crarikshafts' I9', since vthe yoke .I2'is`likewisevoperatively mounted onthe eccenthe main crankshaft; The use of a single auxil- A...mechanismI illustrated 5in' Fig. 1 Vwill likewise "maintain any .diameter ofthe internal v gear 9 parallel to itself in all positionsbf movement of the main crank I. the internal gear 9 is made twice" the pitch diameter of the pinion 9, it follows that the center point I3 of the internal gear 9 -is located at any 35 desired point on the pitcln circle of the pinion 6. If the kcenter point I3-of-the internal gear; v-9 is moved on the-pitchcircle of the pinion 6;

vsaid'pinion being shown in full 1ine`s,.to the right or left vfrom the position shown in Fig. 1,\it will change the eccentricity e ofthe-center'point I3 with respect to the axis"l4. of the main-crankshaft I decreasing it with-a movement to the right and increasing it `.with a movement tothe left. This wouldy necessitate a corresponding-ide'- crease or increase in fthe throw e of the auxiliary gear 9, the throw -e of the' auxiliary cranks I9 1 should be made equal to the distance e between' the axis I4 of the main crankshaft I'and the 5;; point of intersection' I3' ofthe pitch circles of the two pinions 6.

Referring now to the embodiment illustrated in Figs. 4 and 5, themechanism therein illustrated is very similar to that of' Figs. 1, Zand 3, except yfor the' means provided for 'maintaining the vinternal gear in a circular movement of such a nature that any diameter.v of said internal gear remains parallel to itself in all positions ofthe crank movement. j In Figs. 1 lthrough 3, thisv cir- G5 cular movement of the internal gear is accom piished through the use of lone-.or more auxiliary crankshafts I 9, whereas in theembodiment illustrated in Figs. 4 and 5 Vit is accomplished through the use of an inner frame, an outer frame and ya ilxed guide, the inner frame sliding within the outer fremd-the cuter frame sliding between fixed guides, the sliding surfaces between the inner frame'and the outer fra-me being at an angle to the sliding surfaces between the outer "5 frame and the fixed guides. .Due to thefsiniilarity Iiary crankshaft such asthe crankshaft I9in the f Since the pitch diameter of *l cranks I9, in order `to maintain'the proper parev -equal to each other crankcase, has two sleeves 3b, said sleeves being rotatably mounted on adjacent crank pins 4b. Eccentric'sheaves lb, only one of which is shown in Fig, 4 for clearness, and a pinion 6b are made integral with or rigidly fastened to each of the sleeves 3b. Each of the eccentric sheaves 5b is provided with an eccentricstrap 1b, to which a piston rod lb, which receives and transmits the thrust from the piston, is attached; power being taken from one or both ends of the crankshaft |b or at a point between the ends of the same. Each of the pinions 6b mesh directly with internal gears lb, which have pitch diameters and likewise equal to twice that of the pinions lb, said internal gears 9b being operatively mounted on the periphery |b of the `eccentrica'lly located circular web or cheek ||b of the main crankshaft |b between adjacent crank throws. The eccentricity or `throws of all eccentric sheaves 5b are made equal, one to another. and likewise equal to the throws of the cranks Ib upon which they .are mounted. The pitch diameters of the pinions 6b are made equal and greater than twice the throws of the cranks I'b upon which they are mounted. The internal gears 3b are rigidly fixed to an inner frame member |2b. The internal gears 3b and the inner frame member |2b. .to which they are attached, are all mounted on the eccentrically located-4 periphery |0b of the web` or cheek Hb of the crankshaft Ib, be-v tween adjacent crank throws, said periphery Illb` forming the bearing surface of the inner frame member |2b. The center point lib of the internal gear lb is thus located eccentricali ly with respect to the 'axis `|41: of the crankshaft Ib, the extent of this eccentricity being designated as e. The internal gears 3b are rigidly attached to the inner sliding frame member |2b yin a manner which will prevent tangential movement under operating conditions but which will permit some adjustment of the position of the internal gears 3b' in relation to the inner frame member |2b, in a tangential direction about their center points lib, for the purpose of correcting possible mis-alignment of the piston rod path resulting from gear tooth'wear. Tangential adjustment of the internal gears 9b with respect to the inner sliding frame member |2b may be accomplished by providing cap screws Ib fitting into slotted screw holes |6b in the gear ring lb and screwed into the inner sliding member |2b. y

The inner sliding frame member .|2b, to which the internal gears lb are fastened, is mounted between the vertical guide surfaces 3l) of an `outer sliding frame 3| in a manner to permit an up-and-down movement of the inner frame member |2b within the outer. sliding frame 3|. The outer sliding frame member 3| is mounted between fixed horizontal guides 22, only one of which is shown, which are fastened to or made integral with the crankcase, saidmoimting being of a type which will permit a horizontal back-and-forth movement of the outer frame member 3| between the fixed guides 32. This up-and-down vertical movement of the inner vner sliding frame |2b, in either direction, being equal to-2e, this movement being in a plane normal to the axis |4b of the crankshaft lb. The outer framemember 3| moves-with a rec iprocating simple harmonic motion, the movement of the inner 'frame |2b being a circular motion, the diameter ofthe circular path traversed by any point.on the frame |2b being 2e. A tongue 33 on the guide surfaces 30 of the outer sliding frame member 3| fits between the guiding surfaces 34 of the inner sliding frame member I2b. A similar construction is employed between the outer slidingv frame member 3| and the Vfixed guide 32. i i

Since the pitch diameter of the internal gear 9b is made twice the pitch diameter of the pinion 6b, the lcenter point |3b of the internal gear 9b is always located at some point, which may be any point selected, on the pitch circle of the pinion 6b, thereby maintaining the internal gear 9b and'pinion 6b in mesh with each other. Because there is no tangential movement of the gear 3b in the frame member |2b about the center point 13b of the gear, but only a circular movement oi' the gear 9b in a circular path having a radius e, any diameter of the internal gear 9b always remains parallel to itself in all positions of the crank movement and the center' point 35 of any eccentric sheave 5b attached to sleeves 3b and pinions 6b always follows a straight-line path passing through the axis |4b of crank rotation. The extent of the move-- ment of the eccentric sheave center point 35 in any one directionis equal to four times thc throw of the crank Ib.

Referring now to the motion conversion mechanism illustrated in Figs; 6 and '7, a built-up type single or multi-throw crankshaft 40, supported by main bearings 4| mounted in the crankcase, has a sleeve 42 rotatably mounted on a crank pin 43. lTwo eccentric sheaves 44 and a pinion 45 are made integral 4with or rigidly fastened to the sleeve 42. Each of the eccentric sheaves 44 is provided with an eccentric strap 46 to which a piston rod 41, which receives and transmits the thrust from the piston, is attached, power being taken from one or both ends of the crankshaft 40, or at a point between the endsof the same. The eccentricity or throws of al1 eccentric sheaves 44 are made equal, one to another, and likewise equal to the throw of the main crank pin 43 upon which they are mounted. The pitch diameter of the pinion 45 is made greater than twice .the throw of the main crank pin 43 upon which it is mounted.

The pinion 45 meshes directly with an internal gear 48 which is rigidly fastened to a yoke or frame member 49, the yoke member 4B being operativelymounted on the crank pins 50 of two auxiliary crankshaits 5|, which are supported on auxiliary crank main bearings .52 mounted in the crankcase. The auxiliary cranks 5| are driven at the same angular velocity and in the same direction of rotation as that of the main crankshaft 40 by the rigid, one-piece connecting of the crank pins 54 and 55 about their axes of rod or link member 53, which is operatively connected to acrank pin 54 on the end of the main crankshaft 40 and to crank pins 55 on the ends of each of the auxiliary crankshafts the throws of all these crank pins 54 and 55r being made equal, one to another, said throw` being designated as W, in Fig. '7. The throw W of these crank pins 54A and 55 of the'crankshaft driving gear may be v'rnade any amount desired within the limits of practical .,design, the throw W being entirely independent of and unrelated to the throw T of the main crank Vpin 43 or the throws e of the two auxiliary crank pins 50.

The internal gear 48 which is rigidly fastened to the yoke member 49 has a pitch diameter which is made twice that of the pinion 45.` The center point 59 of the internal gear 48 is always located at some point on the pitch circle of the pinion 45, this internal gear center point 59 being eccentrically located with respect to the axis 40a of the main crankshaft 48, the extent of the eccentricity being designated as e. The

throws e of each of the auxiliary crankshafts 5|A are made equal to this eccentricity e of the center point 59 of the internal gear 48 rwith respect to the axis 40a of the main crankshaft 48, the angular position of each of the auxiliary crank pins 58 around their axes 5|a of rotation being made alike and likewise the same as the angular position of the internal gear center point 59 around the `axis 40a ofthe main crankshaft 40. In the apparatus shown in Figs. 6 and 7, the center point 59 of the internal gear 48 is spaced 180 degrees from the axis 43a of the main crank pink 43 around their common yaxis of rotation-40a of the main crankshaft 40. This center point 59v of the internal gear 48 may be placed in `any rotation are the same and may or may not conform to the angular position of eitherthe main crank pin 43 or of the auxiliary crank pins 50 about their respective axes of rotation.

, The circular movement of the auxiliary crank pins 59 about the axes 5|a of the auxiliary crank-` shafts 5|v and the circular movement of thefyoke member 49, which is operatively mounted von the auxiliary crank pins 50, is caused by the movement of the main crankshaft 40 about its axis 40a,

the main crankshaft 40 driving the auxiliary crankshafts 5| through the rigid, one-piece connecting rod or link member 53, or through a gear train` or through a sprocket chain, or other suitable means. The diameter of the circular path of the movement of each'of the auxiliary crank ment.

angular position with respect to the main crank pin 43 around their common axis-of rotation 40a,

providingthis internal gear` center point'59 is located at some point on the pitch circle of the piniony 45. The angular position of this internal gear center point 59 with'respect to the main crank pin 43 around their common axis 40ar is designated vas A, A being the angle between the line passing through the internal gear center point 59 and the axis 40a of the main crankshaft and a. line passing through this same axis 40a of the main crankshaft 40 and the axis 43a of the main crank pin 43.

The crank pins are located andvmounted on the ends of the auxiliary crankshafts 5| andthe crank pin/54 is located and mounted on the end of the main crankshaft 49 in such manner that both of the crank pins 50 of these .auxiliary crankshafts 5| occupy angular positions around their axes 5| a of rotation similar to and corre' sponding with the angular position of the internal gear center point 59 around the axis 40a of the main crankshaft 40. In other words, the main and auxiliary crankshafts are operatively connected in such manner that all rotate in the same direction and at thesame angular-velocity, but these main and auxiliary crankshafts are connected and timed so that both auxiliary crank pins 50 and the internal gear center point 59 occupy pins lland ofthe yoke member 49 is equal to 2e. 'I'his circular movement of the yoke member 49 isrof such a nature that any line takenon the yoke 49 always remains parallel to itself in all positions of the main crank v4|) and yoke 49 move- Likewise, since the internal gear 48 is rigidly' fastened to the yoke member '49, any diameter of the gear 48 always remains parallel to itself in all positionsof the movement of the main crank- 40. The yauxiliary rcrankshafts 5| act in the capacity of idler cranks driven by the main crankshaft, as hereinbefore described, theA primary purpose of these auxiliary cranks 5| being that of maintaining the yoke member 49 in a circulan motion `such that it always remains parallel to itself in all positions ,of the crank movement and insures the continuous proper engagement of the pinion 45 with the internal gear 48. Since the throws e of these auxiliary cranks 5| are made such that the center point 59 of the internal gear 48 is located and maintained at some point. on the pitch circle of the pinion v45, ther continuous proper meshing of this pinion 45 with the internal gear 48 is assured.' While two auxiliary crankshafts 5| are shown operatively connected to the yoke member 49 in Figs. 6 and '7, any greater number of auxiliary crankshafts 5| maybe so connected to the yoke member, within the limits of practical design. f

The internal gear 48 is adjustablymounted on y the yoke member 49 in a manner similar to that previously described for Figs. 1, 2, 3, 4 and 5, this adjustable mounting of the gear plate 58 on the yoke member 49 involving the useof cap screws f 56 fitting into slotted screw holes 51 in the gear ring or plate 58, the cap screws 56 being screwedi into the yoke,l member 449. y

Because there is no tangential movement of the internal gear 48` with respect to its center point 59, any liner on said gear 48 always remaining parallel to itself in all positions of the crank and yoke movement and because of ,the twoto one gear ratio relationship of the internal gear 48 to the pinion 45, said gears being maintained in continuous proper engagement by the circular moveidentical corresponding angular positions around f their respective axes of rotation. `The auxiliary crankshafts 5| may be so driven by and oper-A atively connected ftothe main crankshaft 48 as hereinbefore described through the use of a gear train or a sprocket chain or other suitable driv vthe same results. The angular positions of all ment imparted to the'yoke 49 and internal-gear 48 -by the auxiliary crankshafts 5|, the pinionY 45 attached to the sleeve 42 and eccentric sheavesv 44 all rotate at the same absolute angular velocity as, but in the opposite direction of rotation from, that of the main crankshaft 40, thereby fulfilling Aall requirements necessary toinsure the straightline movement of the center points'of these eccentric sheaves 44, in paths which pass through the axis 40a of the maincrankshaft 40'the extent of said movement in any one direction beingvequal to the crankshaft and 6 to four times the throw T of the main crank pin 43.

It is to be understood that in all of the mechanisms herein described, reciprocatory movement may be transmitted to the eccentric strap or straps for conversion into rotary movement, as in the case of an internal combustion engine, a' steam engine, etc., or rotary movement may be applied to the crankshaft for conversion into reciprocatory movement, asin the case of a plunger pump, a compressor, etc. It is to be further understood that the application and use of the mechanisms herein described isv not confined to engines, compressors, pumps, etc., but may be used wherever it is desired to convert reciprocating movement into rotary movement and vice versa.

In all of the forms of the driving gear mechanisms embodying the invention as previously described, a built-up, demountable Vtype crankshaft has been specified in the descriptions and illustrated in the various figures. Thisv is the -pre ferred type for use in thesedrve gear mechanisms. However, a solid, one-piece type of crankshaft, with split-type eccentric sheaves, split sleeves and sleeve bearings, could be used in these mechanisms, if so desired. Crankshafts used in these mechanisms may be either of the' single or multi-throw type.

In the particularform ofbuilt-up crankshaft shown in the different figures, the main crankshaft journais are actually circular shaped web members between adjacent crankthr uws, these web members being made concentric with the axis of the crankshaft and made sui'ciently largehto completely surround and include the crankpins in their side surfaces, the main bearing journalxsurfaces being the peripheral face portions of these circular webs. Such a design is made. practicable by the fact that the throw of the main crank used in the driving gear mechanisms,is only one-half of that required in the usual connecting-'rodeandcrank type of driving gear, having a total piston stroke equal to that of these/'drive g'ea'r mechanisms. It is, therefore, possible to empioyjuus type yof main crankshaft journaldesign inthese mechanisms without making'it necessary to increase the diameter of thesemain bearingsbeyond practical limits or greatly in excess of that `required for the usual connecting-rod-and-crank type of drive gear having an equivalent piston stroke, etc. -Such a main bearing design makes possible a substantial reduction in the total length of theV crankshaft, at the same time materially inl creasing both its strength and stiffness.

Fig. 1), for various angular positions A, (wherein A is the angle between the line connecting the main crank pin axis with the main crankshaft axis, and the line connecting the center point (Il of Fig. 1) of the internal gear (9 of Fig. 1) with .the main crankshaft axis (I4 of Fig. 1).

For values of A ranging from 0 degrees to 90 .degrees For value of A ranging from 90 degrees to 180 i degrees S =T sin (A-90) C=T cos (zi-90) Total stroke==4 T In the above formulas, S and C are arbitrary symbols to facilitate calculation. These formulas apply to all of the devices herein described, either in the case Where the motion conversion mechanism serves the eccentric sheave or sheaveson each of two adjacent crank pins or serves the eccentric sheave or sheaves on only one crank pin.

internal gear and one pinion In all of the forms of these motion conversion mechanisms herein described, perfect balance of all operating parts may be obtained .by first balancing the sleeve land. the masses it carries, such as eccentric sheaves, about the axisI of the crank pin and then balancing the whole assembly of sleeve, eccentric sheaves, crank pins, crank webs and unbalanced reciprocating forces, said balancing being accomplished by the proper attachment of suitable masses in the form of counterweights,

bers.

Formulas are given below for the relationship of the eccentricity e of the internal gear center point (I3 of Fig. 1) with respect to the axis (I4 of Fig. 1) of themain' crankshaft, the throw T of the main crank pin (4 .of Fig. l) the throw e of the auxiliary cranks (e of Fig. 1),..the pitch circle radius Lof the internal gear (9 of Fig. l) and the radius r of the pitch circle of the In the devices illustrated in Figs. l through 5, I have shown two pinions 8 on adjacent main .crank pins and two internal gears 9 connected together and arranged to control the movement of both pinions 6. I may, however, use only one where the device is intended to serve only one main crank pin. The arrangement shown is advantageous, however, in that it permits a reduction in the number of necessary moving parts and likewise permits a reduction in the length of the crankshaft.

A' further characteristicv and advantage of these mechanisms liesin the fct that the straight-line path of the eccentric movement, and, therefore,

'the centerline of all pistons, cylinders, etc. connected thereto, may be placed in any angular position around the axis of the main crankshaft, provided same vis made normal to and passes through this axis of the main crankshaft.

A further characteristic and advantagemLall these mechanisms lies in the fact that the diameter of the crank pins is not limited in relation .to

to the reciprocating mempinion (6 of 75 the sleeve.

the throw of the main cranks, as is the case in many existing straight-line motion conversion mechanisms, such as those wherein the pitch diameter of the eccentric driving pinion, which is mounted on ,asleev'e on the crank pin, is made equal to the stroke-of the crank, the'eccentric pinion engaging an internal fixed gear, made concentric with-the crankshaft axis pitch diameter twice that of the pinion. Since in these previous existing mechanisms, the pitch diameter ofthe pinion is made equal to the crank stroke, the diameter of the crank pin, upon which this pinion and sleeve are mounted, mst of necessity be made less than this crank stroke by an amount approximately equal to the sum ofthe depth of the gear teeth plus twice the thickness of For examplfinradevice of the type and havinga under discussion, which has la total piston rod stroke of four inches and a crank stroke of two inches, and assuming a tooth depthlof` 1/i inch and a sleeve thickness of inch, the'maximum possible diameter of the crank pin under such conditions would be 2"1/4{-%"-%" or 1"/ which is, obviously, a size far below the normal requirements in this regard.

A still further characteristic and advantage of all these mechanisms lies in the fact that the torque available at the main drive shaft may be changedbetween wide limits by simply changing the pitch diameter ef the eccentric drive pinion (such as pinion 6 of Fig. 1) and of the internal gear (9 of Fig. 1) meshed therewith, as needed to maintain their specified relationship, one with another, but without changing the thrust load delivered to the piston rod and without changing the stroke of the main crank. The torque at the main drive shaft of thesefmechanisms may thus be made any selected amount, below two times but above one times that delivered by a simple orthodox"connectingrodand-crank drive, having a crank throw equal to that of the main crank used in the motion conversion mechanism, the connecting rod of the timple crank drivef being considered to be of infinite length'in calculatingr the torque, the piston loading in each case being the same. 'f The equivalent stroke, (Es) of a simple orthodox connecting-rod-and-crank type of driving gear, having a. connecting rod assumed to be of inlinite length, which will'deliver the same torque at the drive shaft, under the sarnepiston loadconditions as that delivered by these motion conversion mechanisms, may be expressed'as follows:

El=X (VT +r) Where T equalsV the throw of the main crank and r equals the radius of the pitch circle of the ecV 1i is evidentfreni this formule. that, if the velue as small as possible in relation to the strokeof the main crank, within the limits of practical design, but never made equal to orless than said stroke of the main crank, in order to increase the torque available at the main drive shaft.

If the pitch diameter selected for the eccentric drive pinion of any of these mechanisms were to be made an amount equal to the stroke of the main crank, the need for mounting the internal gear, which meshes directly with this pinion, on a-yoke or frame member to which a circular motion is imparted, would be eliminated and this internal gear would then, under such conditions,

be mounted in a fixed position concentric with the axis of the main crank, the same as in other existing mechanisms. The pitch diameter of the pinion used in allmechanisms herein described has been specined as anylselected amount greater than the stroke of the main crank, in order to ,attain the improvements and advantages as described.

These various mechanisms may beused to advantage in connection with radial type engines and oppsedcylinder type engines, pumps, etc., especially if co-axial cylinders,v with opposedpistons, connected by a common, one-piece, rigid connecting rod or articulated link and master rod, are used. These mechanisms may likewise be used advantageously in connection with opposed-piston, single or double-acting, co-axial tandem cylinder type engines. j

On account of the back-lash present, to a greater or lesser degree, in all gear drives, there is a slight side-play? present in all pistons which are directly and rigidly connected by relatively short piston rods to the eccentrics, of all mechanisms herein i described; this side-play .being caused by the slightmis-alignment of the 'path of the eccentric movemenaresulting from thev relative movement; back-lash, of the mating gear I teeth, one tooth within the other. The extent of- -this side-play of' th/'piston rod is 1n proportion tothe amount [of th`v operating clearance provided betweenthemainggear teeth, and varies in its effect from/zero, when the piston rod is at .mid-stroke, to afma imum, when the piston rod is at veither end o'fjilhe'stroke.v 5

kof T, which is the radius ofthe main crank circle,

is kept constant, the value of Ee is diminished as the value of 1' is increased. In other words, with the throw T of the main crank of the mechanism l constant, the torque, delivered at the drive shaft' of the mechanism,idecrea'ses as the pitch diameter of the eccentric drive pinion (such as pinion `6 of Fig.2) is increased.

In view of this characteristic, the pitch diameter selected for the eccentric drive pinions in all of the mechanisms, which are intended for use in connectionwith pumps, air compressors and other machines, wherein power is applied to the drive shaft and converted into reciprocating motion, should be made large in relation to the stroke of the main crank pin, in order to reduce the torque requirements at the drive shaft. On the other hand, the pitch diameter selected for the eccentric drive pinions of all mechanism whichare intended for use in connection with power generating equipment, such asiinternal combustion eny gines, steam engines and other machines, wherein l force is applied to the pistons, piston rods, etc.,

In vi ci these-condicionan isi-sometimes de- I. sirable vto, provide an articulated type of connection between pistons and eccentrics, which are. to

be `fiinicny 'connected by relatively Sheri piston rod's, oneto therbther, ininllmechanisms wherein roughly tlnished'or poorly tted gears are used. In ,they of co-"axial opposed cylinder en gineswith,gearsof suchgtype, the Pistons may be connected directlygto each other, through a common eccentric on the centrally located crankshaft, by a lmaster-red and articulated link -type of connection. In the ,event only onel piston is to be directly connected to the eccentric of such an engine, an articulated linkftype of connection may 4:be used. In all such cases, ajointed connection (wrist pin),` should be provided -between the piston rods and the pistons.

In all mechanisms wherein closely tted, highly accurate. and nlshed gearing is employed, such as the kind of gearsrused in the best aircraft engines, the extent .of this back-lash" and resulting mis-alignment' and side-play i of the pistons, piston rods, etc., is negligible and may be disregarded. Under suchconditions, the rigid `piston rod type .of connection between piston rod and eccentric strap and between piston rod and piston may be used, without detrimental effects or increase in theffrictional losses.. The usual clearance provided between the pistons and cylinder walls should be sufficient to take-up the negligible side-play present under such conditions, thereby relleving the pistons of any possible side thrust resulting from same.

The invention is not limited to the preferred embodiments, which have been given merely for illustrative purposes, but may be otherwise embodied or practiced within the scope of the following claims.

I claim:

1. Motionv conversion mechanism, comprising a crankshaft supported on bearings, a crank pin on a crank arm of said crankshaft, a sleeve rotatably mounted on said crank pin, an eccentric sheave and a pinion rigidly fixed to said sleeve, a strap operatively mounted on said eccentric sheave, the eccentricity of the eccentric sheave on the crank pin being equal to the throw of the crank arm, the pitch diameter of said pinion being greater than twice the throw of the crank arm, an internal gear having a pitch diameter twice the pitch diameter of said pinion and maintained in mesh therewith, means forrotating the center point of said internal gear about the axis of the crankshaft in the same direction and at the same angular velocity as the crank pin, and means for maintaining any diameter of said internal gear parallel to itself in all positions of the crank movement.

2. Motion conversion mechanism, comprising a. crankshaft supported on bearings, a crank pin on a crank arm of said crankshaft, a sleeve rotatably mounted on said crank pin, an eccentric sheave and a pinion rigidly fixed to said sleeve, a strap operatively mounted on said eccentric sheave, the eccentricity of theeccentric sheave on the crank pin being equal to the throw of the crank arm, the pitch diameter of said pinion being greater than twice the throw of the crank arm, an internal gear having a pitch diameter twice the pitch diameter of said pinion and maintained in mesh therewith, said internal gear being operatively mounted on the crankshaft in an eccentric position with reference to the axis of the crankshaft such that" said internal gear and pinion are maintained in mesh with each other, and means for maintaining anyl diameter of said internal gear parallel to itself in all positions of the crank movement.

3. Motion conversion mechanism, comprising a crankshaft supported on bearings, a crank pin on a crank arm of saidl crankshaft, a sleeve rotatably mounted on said crank pin, an eccentric sheave and a pinion rigidly xed to said parallel to itself in all positions of the sleeve, a strap operativelymounted on said eccentric sheave, the eccentricity of the eccentric sheave on the crank pin being equal to the throw of the crankarm, the pitch diameter of said pinion being greater than twice the throw of the crank arm, an internal gear having a pitch diameter twice the pitch diameter of said pinion and maintained in mesh therewith, said internal gear being operatively mounted on the'periphery of a web of the crankshaft between adjacent crank throws'in an eccentric position with reference to the axis of the crankshaft such that said internal gear and pinion are maintained in mesh with each other, and means for maintaining any diameter of said internal gear parallel to itself in all positions of the crank movement.

4. Motion conversion mechanism, comprising a main crankshaft supported on bearings, a.

crank pin on a crank arm of said main crankshaft, a sleeve rotatably mounted on said main crank pin, an eccentric sheave and a pinion rigidly fixed to said sleeve, a strap operatively mounted on said eccentric sheave, the eccentricity of the eccentric sheave on the main crank pin being equal to the throw of the main crank arm, the pitch diameter of saidpinion being greater than twice the throw'of the main crank arm, an internal gear having a pitch diameter twice the pitch diameter of said pinion and maintained in mesh therewith, said internal gear being rigidly fixed to a yoke, at least one or more auxiliary crankshafts, said yoke being operatively mounted on the crank pin or pins of said auxiliary crankshaft or crankshafts, means for rotating said auxiliary crankshaft or crankshafts in the same direction and at the same angular velocity as that vof said main crankshaft, the throw or throws of said auxiliarycrank pin or pins being all made equal to the distance between the axis of the main crankshaft and the `center point of said internal gear, whereby any diameter of said internal gear is maintained parallel to itself in` all positions of the crank movement.

5. Motion conversion mechanism, comprising a main crankshaft vsupported on bearings, a crank pin on a crank arm of said main crankl shaft, a sleeve rotatably mounted on said main arm, an internal gear having a pitch diameterA twice the pitch diameter of said pinion and maintained in mesh therewith, said internal gear being rigidly fixed to-a yoke, at least one or more auxiliary crankshafts, said yoke being operatively mounted ron the crank pin or pins of said auxiliary crankshaft or crankshafts, means operatively connected to said `main crankshaft for rotating said auxiliary crankshaft or crankshafts in the same direction and at the same.

angular velocity as that of said main crankshaft, the throw or throwsy of said auxiliary crank pin or pins being all made equal to the distance between the axis of the main crankshaft and the centerr point of said internal gear, whereby any diameter of said internal gear is maintained main crank movement.

6.'Motion conversion mechanism, comprising a main crankshaft supported on bearings, a crank pin on a crank arm of said main crankshaft, a sleeve rotatably mounted on said main crankpin, an eccentric sheave and a pinion rigidly fixed to said sleeve, a strap operatively mounted on said eccentric sheave, the eccentricity of the eccentric sheave on the main crank pin being equal to the throw of the main crank arm. the pitch diameter of said pinion being greater than twice the throwr of the main crank arm, an internal gear having a pitch diameter twice the pitch diameter of said pinion and maintained in mesh therewith, said internal gear being rigidly fixed to a yoke, at least one or more auxiliary crankshafts, said yoke being operatively mounted on the crank pin or pins of said auxiliary crankshaft or crankshafts, means operatively mounted on the main crankshaft in an eccentric position with reference to the axis of the main crankshaft such that said internal gear and yand said auxiliary crankshaft yor crankshafts is or are rotated in the same direction and at the same angular: velocity as that of said main crankshaft, the throw or throws of said auxiliary crank pin or pins being all made equal to the distance between the axis of the main crankshaft and the center point of said internal gear, whereby vany diameter of said internal gear is maintained parallel to itself in all positions of the main crank movement.

7. Motion conversion mechanism, comprising a main crankshaft supported on bearings, a' crank pin on a crank arm of said main crankshaft, a sleeve rotatably mounted on said main crank pin, an eccentric sheave and a pinion rigidly fixed to said sleeve, a strap operatively mounted on said eccentric sheave, the eccentricity of the eccentric sheave on the main crank pin being equal to the throwof the main crank arm, the pitch diameter of said pinion being greater than twice the throw of the main crank arm, an internal gear having a pitch diameter twice the pitch diameter of said pinion and maintained in mesh therewith, said internal gear being rigidly fixed to a yoke, at least one or more auxiliary crankshafts, said yoke being operatively mounted on the crank pin or pins of said auxiliary crankshaft or crankshafta meansroperatively mounted on the periphery of @web of vthe main crankshaft between adjacent crank'throws for rotating said auxiliary crankshaft or crankshafts in the same direction and at the same angular velocity as that of said main crankshaft, the throw or throws of said auxiliary crank pin or pins being all made equal to the distance between the axis of the main crankshaft and the center point of said internal gear, whereby any diameter of said internal gear is maintained parallel` to itself in all positions of the main crank movement.

8. Motion conversion mechanism, comprising a. crankshaft supported-on bearings, a crank pin on a crank arm of each of* two adjacent crank throws, a sleeve rotatably mounted on each crank pin, an eccentric sheave and a pinion rigidly fixed to each of said sleeves, a strap operatively mounted on each of said eccentric sheaves, the eccentricity of each eccentric sheave on each crank pin and the throw of each adjacent crank all being equal, the pitch diameter of each of said pinions being made equal, one to l another and likewise greater than twice thev throw of the crank arm, two internal gears each having a pitch diameter twice the pitch diameter of veach of said pinions, each of said internal gears being operatively mounted on the periphery of a web of the crankshaft between adjacent crank throws in an eccentric position with reference to the axis of 'the crankshaft such that each of said internal gears is maintained in mesh with its pinion, and means for maintaining any diameter of each of said internal gears parallel to itself in all positions of the crank movement.

9. Motion conversion mechanism, comprising a crankshaft supported on bearings, a crank pin on a crank arm of said crankshaft, a sleeve rotatably mounted on said crank pin, an eccentric sheave and a pinion rigidly fixed to said sleeve,

'a strap operatively mounted on said eccentric sheave, the eccentricity of the eccentric sheave on the crank pin being equal to the throw of the crank arm, the pitch diameter of said pinion being greater than twice the throw of the crank arm, an internal gear having a pitch diameter twice the pitch diameter of. said pinion and maintained in mesh therewith, said internal gear being fixed on an inner frame which is operatively mounted on the crankshaft\ in an eccentric position with reference to the axis of the crankshaftl such that said internal gear and pinion are maintained in mesh with each other, an outer frame on which the inner frame is adapted to slide, and a fixed guide on which the,

outer framev is adapted to slide, the sliding surface-between the inner and outer frames and the sliding surface between the outer frame and fixed guide being at an angle to each other.

, WILLIAM J. CULBERTSON. 

